According to initial information, there were as many as four subjects aboard and under investigation, law enforcement sources told ABC News. The investigation was centered on a principal suspect who barricaded himself in bathroom and three others possibly viewed as spotters.

The main subject of the investigation apparently spent a considerable amount of time in the restroom, the law enforcement sources said. When the subject exited restroom, airline personnel searched it with negative results.

FBI officials from the Detroit office were on the scene but did not initially board the aircraft. They had information that the man in the bathroom could be Nigerian and that the crew broke down the bathroom door and placed him into custody.
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Two passengers who were aboard today's flight downplayed the latest incident. One told ABC News that the flight landed and passengers were held on the plane for 15 minutes until customs agents arrived. Both said they did not see anyone arrested.